Composition of glass for the production of glazing

Abstract

A glass composition of the soda-lime-silicate type is described which includes, by weight, the following coloring agents: 0.2-0.45% of Fe 2 O 3 (total iron), 2-8 ppm of Se, 0-20 ppm of CoO, and 0-80 ppm of NiO. The coloring agents satisfy the relationship, 0.7<(200×NiO) +(5000×Se)+(6×Fe 3+ )/(875×CoO)+(24×Fe 2+ )<1.6 in which the NiO, Se, Fe 3+ , CoO and Fe 2+ contents are expressed in ppm, Fe 3+ and Fe 2+ are the content of ferric iron expressed in the form of Fe 2 O 3 and FeO, respectively. The composition has a redox from 0.28 to 0.5, an overall light transmission under illuminant A (T LA ) greater than 65% and a selectivity (SE) of greater than 1.25, when measured for a thickness of 3.85 mm. A window formed from at least one glass sheet produced from the aforementioned composition is also described.

1. A glass composition comprising, in weight percent: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   SiO 2   
                   64-75% 
                 
                     
                   Al 2 O 3   
                   0-5% 
                 
                     
                   B 2 O 3   
                   0-5% 
                 
                     
                   CaO 
                    5-15% 
                 
                     
                   MgO 
                   0-5% 
                 
                     
                   Na 2 O 
                   10-18% 
                 
                     
                   K 2 O 
                   0-5% 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
               
            
           
         
       
       and coloring agents which comprises, in weight percent: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.2-0.45% 
                 
                     
                   Se 
                    2-8 ppm 
                 
                     
                   CoO 
                   0-20 ppm 
                 
                     
                   NiO 
                   0-80 ppm 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
         wherein said coloring agents satisfy the following relationship: 
         0.7<(200×NiO)+(5000×Se)+(6×Fe 3+ )/(875×CoO)+(24×Fe 2+ )<1.6 wherein the NiO, Se, Fe 3+ , CoO and Fe 2+  contents are expressed in ppm, Fe 3+  is the content of ferric iron expressed in the form of Fe 2 O 3  and Fe 2+  is the content of ferrous iron expressed in the form of FeO, 
         wherein the composition has an excitation purity of less than or equal to 2%, a redox from 0.28 to 0.5, an overall light transmission under illuminant A (T LA ) greater than 65% and a selectivity (SE) of greater than 1.25, when measured for a thickness of 3.85 mm. 
       
     
     
       2. The composition as claimed in  claim 1 , wherein the composition comprises: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.2-0.3% 
                 
                     
                   Se 
                    2-8 ppm 
                 
                     
                   CoO 
                   0-20 ppm 
                 
                     
                   NiO 
                    0-5 ppm 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
         and the composition has a redox of greater than 0.4. 
       
     
     
       3. The composition as claimed in  claim 2 , wherein the composition has an excitation purity of less than 1%. 
     
     
       4. The composition as claimed in  claim 2 , wherein the composition does not comprise NiO and comprises: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.2-0.25% 
                 
                     
                   Se 
                    4-7 ppm 
                 
                     
                   CoO 
                   10-20 ppm. 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
               
            
           
         
       
     
     
       5. The composition as claimed in  claim 1 , wherein the composition comprises: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.35-0.45% 
                 
                     
                   Se 
                    2-8 ppm 
                 
                     
                   CoO 
                   0-10 ppm 
                 
                     
                   NiO 
                   0-80 ppm 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
         and the composition has a redox of greater than or equal to 0.34. 
       
     
     
       6. The composition as claimed in  claim 1 , wherein the composition has a selectivity of greater than 1.3. 
     
     
       7. The composition as claimed in  claim 5 , wherein the composition comprises: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.39-0.45% 
                 
                     
                   Se 
                    3-6 ppm 
                 
                     
                   CoO 
                    0-6 ppm 
                 
                     
                   NiO 
                   0-15 ppm. 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
       8. The composition as claimed in  claim 1 , wherein the composition has an excitation purity of less than or equal to 1%. 
     
     
       9. The composition as claimed in  claim 1 , wherein the composition has a color rendering index (Ra) of at least 94. 
     
     
       10. The composition as claimed in  claim 1 , wherein the composition further comprises at least one optical absorption agent selected from the group consisting of CeO 2 , TiO 2 , V 2 O 5 , WO 3  and La 2 O 3 . 
     
     
       11. The composition as claimed in  claim 10 , wherein the total content of said optical absorption agent is less than 1% by weight. 
     
     
       12. A window, comprising at least one glass sheet which comprises the composition as claimed in  claim 1 . 
     
     
       13. The window as claimed in  claim 12 , wherein the sheet has a thickness between 0.8 and 10 mm. 
     
     
       14. The window as claimed in  claim 13 , wherein the sheet has an overall light transmission under illuminant A (T LA ) of at least 70% for a thickness of 3.85 mm. 
     
     
       15. The composition as claimed in  claim 6 , wherein the composition comprises: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Fe 2 O 3  (total iron) 
                   0.39-0.45% 
                 
                     
                   Se 
                    3-6 ppm 
                 
                     
                   CoO 
                    0-6 ppm 
                 
                     
                   NiO 
                   0-15 ppm. 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
               
            
           
         
       
     
     
       16. The composition as claimed in  claim 1 , wherein the composition has a color rendering index (Ra) greater than 96.